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<h2><span class="refentrytitle">Class optional_last_value&lt;void&gt;</span></h2>
<p>boost::signals2::optional_last_value&lt;void&gt; &#8212; Evaluate an InputIterator sequence.</p>
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<h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2>
<div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: &lt;<a class="link" href="../../signals2/reference.html#header.boost.signals2.optional_last_value_hpp" title="Header &lt;boost/signals2/optional_last_value.hpp&gt;">boost/signals2/optional_last_value.hpp</a>&gt;

</span>
<span class="keyword">class</span> <a class="link" href="optional_last__idp75552224.html" title="Class optional_last_value&lt;void&gt;">optional_last_value</a><span class="special">&lt;</span><span class="keyword">void</span><span class="special">&gt;</span> <span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
  <span class="comment">// types</span>
  <span class="keyword">typedef</span> <span class="keyword">void</span> <a name="boost.signals2.optional_last__idp75552224.result_type"></a><span class="identifier">result_type</span><span class="special">;</span>

  <span class="comment">// <a class="link" href="optional_last__idp75552224.html#idp75537808-bb">invocation</a></span>
  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <a class="link" href="../../InputIterator.html" title="Concept InputIterator">InputIterator</a><span class="special">&gt;</span> 
    <span class="identifier">result_type</span> <a class="link" href="optional_last__idp75552224.html#idp83102432-bb"><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span></a><span class="special">(</span><span class="identifier">InputIterator</span><span class="special">,</span> <span class="identifier">InputIterator</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
<span class="special">}</span><span class="special">;</span></pre></div>
<div class="refsect1">
<a name="idp162132816"></a><h2>Description</h2>
<p>This specialization of <a class="link" href="optional_last_value.html" title="Class template optional_last_value">signals2::optional_last_value</a> is provided
            to cope with the fact that there is no such thing as an
            <code class="computeroutput">optional&lt;void&gt;</code>, which
            <a class="link" href="optional_last_value.html" title="Class template optional_last_value">optional_last_value</a> would otherwise try to
            use as its <code class="computeroutput">result_type</code>.  This specialization
            instead sets the <code class="computeroutput">result_type</code> to be <code class="computeroutput">void</code>.
          </p>
<div class="refsect2">
<a name="idp162135904"></a><h3>
<a name="idp75537808-bb"></a><code class="computeroutput">optional_last_value</code> invocation</h3>
<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
<pre class="literallayout"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <a class="link" href="../../InputIterator.html" title="Concept InputIterator">InputIterator</a><span class="special">&gt;</span> 
  <span class="identifier">result_type</span> <a name="idp83102432-bb"></a><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span><span class="special">(</span><span class="identifier">InputIterator</span> first<span class="special">,</span> <span class="identifier">InputIterator</span> last<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
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<td><p><span class="term">Effects:</span></p></td>
<td><p>Attempts to dereference every iterator in the sequence <code class="computeroutput">[first, last)</code>.
              </p></td>
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<td align="right"><div class="copyright-footer">Copyright &#169; 2001-2004 Douglas Gregor<br>Copyright &#169; 2007-2009 Frank Mori Hess<p>Distributed under the Boost
    Software License, Version 1.0. (See accompanying file
    <code class="filename">LICENSE_1_0.txt</code> or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)</p>
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